Amelogenesis Imperfecta (AI) are a heterogeneous group of rare genetic diseases transmitted according to various mode of inheritance (X-linked, autosomal dominant, autosomal recessive) affecting the formation/mineralization of tooth enamel. These diseases exist in isolation with clinical manifestations limited to the oral cavity or may be associated to other symptoms in syndromes. Many different genes (AMELX, ENAM, ENAMELYSIN or MMP20, KLK4, DLX3, FAM83H, FAM20A WDR72…) coding for enamel matrix proteins, enamel matrix degrading proteins, proteins involved in hydroxyapatite formation and growth and mineralization processes have been discovered responsible for the clinical phenotypes (hypoplastic, hypomineralized, hypomature) encountered in AI.